Method and product for polishing aluminum with steel wool and a partial ester of phosphoric acid and an aliphatic alcohol



United States Patent METHOD AND PRODUCT FOR POLISHING ALU- MINUM WITH STEEL WOOL AND A PARTIAL ESTER OF PHOSPHORIC ACID AND AN ALI- PHATIC ALCOHOL Barney Joseph Zmoda, New Providence, N..I., assignor to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 5, 1959, Ser. No. 851,018

21 Claims. (Cl. 134-6) The present invention relates to steel wool and to steel wool scouring pads.

Steel wool is widely used as a household scouring agent for the cleansing of soiled cooking utensils, many of which are fabricated of aluminum. In conjunction with this scouring, it is desirable that the surface of the aluminum be left not only clean, but polished as Well. Unfortunately, scouring aluminum with steel wool per se leaves the aluminum surface in a dull and lusterless condition.

In accordance with the present invention a process for cleansing and polishing aluminum comprises scouring aluminum with steel wool in the presence of an aqueous medium and a partial ester of phosphoric acid and an aliphatic alcohol. Another aspect of the present invention is a body of steel wool, such as a scouring pad, containing or impregnated with a partial ester of phosphoric acid and an aliphatic alcohol.

Use of the instant organic phosphate esters in conjunction with steel wool is highly advantageous not only in that it brings about polishing of aluminum, but also in that it substantially completely eliminates seizing between steel wool and aluminum, thereby substantially diminishing the effort required to scour and cleanse soiled aluminum cooking utensils. In addition, it has now been found that metallic surfaces which have been cleansed and polished in accordance with the present invention readily and rapidly drain substantially free of water, apparently as a result of the formation of a residual hydrophobic film or deposit on the surface of the scoured metal by the-organic phosphate ester. This rapid and complete drainage reduces the need for prompt drying and permits drain-drying (i.e. air drying) not only of aluminum ware but also of other metallic objects by eliminating the water staining, etching, pitting and darkening to which metallic surfaces (such as aluminum) are subject when in contact with water for extended periods.

The instant esters are aliphatic partial esters of phosphoric acid. Suitable aliphatic substitutents are those aliphatic radicals containing at least 4 and preferably from 8 to 20 carbon atoms, and mixtures thereof. The aliphatic radicals of the instant esters may be derived from aliphatic alcohols which are straight or branched chain in nature, they may be either saturated or unsaturated, and they may be connected directly to the phosphoric acid moiety or indirectly, as through an intermediate linkage such as a lower polyhydric alcohol, e.g. glycerine. The phosphoric acid portion of the esters may be orthophosphoric acid as well as polyphosphoric acids, e.g. dimers and trimers of orthophosphoric acid corresponding to self-condensation products thereof prepared by elimination of water, e.g. pyrophosphoric acid and tripolyphosphoric acid. The instant partial esters may be employed in the acid (i.e. acidic or unneutralized) form or as neutralized salts. Suitable salts are those of alkali metals such as sodium and potassium, alkaline earth metals such as magnesium, and ammonium and amine salts such as triethanolamine, decylamine, and the like. The esters of the present invention are generally water soluble, i.e. truly soluble or dispersible, examples of suitable esters being sodium butyl orthophosphate (mixed primary and secondary ester), a mixture of approximately equal molar proportions of the mono-ester and di-ester of orthophosphoric acid and lauryl alcohol, di-sodium monomyristal orthophosphate, the sodium salt of the mixed monoand di-ester of orthophosphoric acid and the fatty alcohols derived from coconut oil fatty acid by hydrogenation thereof, the sodium salt of the mixed monoand di-ester of orthophosphoric acid and the fatty alcohols derived from hydrogenated tallow fatty acid, the sodium salt of the mixed monoand di-ester of orthophosphoric acid and oleyl alcohol, and the sodium salt of the mixed monoand di-ester of orthophosphoric acid with either decyl alcohol or tridecyl alcohol. Additional suitable phosphoric acid esters include those derived from pyrophosphoric acid, such as the sodium salt of the di-ester of 2- ethylhexyl alcohol and pyrophosphoric acid, as well as those derived from tripolyphosphoric acid such as, for example, R Na -(P O wherein R is 2-ethylhexyl or capryl. As indicated previously, other alkali metal or alkaline earth metal salts such as the potassium and magnesium salts may be employed in place of the foregoing sodium salts. It is particularly preferred to employ salts of primary and secondary esters of orthophosphoric acid and higher (e.g. C C monohydric primary aliphatic alcohols, for instance disodium monolauryl orthophosphate, magnesium monolauryl orthophosphate, and disodium monooleyl orthophosphate, as these particular ester salts have been found to be characterized by outstanding polishing, anti-seizing, and hydrophobic film-forming properties when used with steel wool to scour aluminum in the presence of water.

Steel wool to be employed for scouring aluminum may be contacted with the instant partial esters at the moment of scouring or at any time prior thereto. Thus, steel wool pads may be impregnated, coated, or otherwise loaded or charged with a suitable ester, and the ester may be employed alone or in "conjunction with additional agents suitable for use with steel wool. The steel wool may be of any grade, e.g. No. 00 or No. Land of any otherwise desirable analysis or carbon content.

It is particularly preferred to employ the instant esters in steel wool which is also loaded with a detergent or detergent composition in order to facilitate soil removal and grease emulsification. As in the case of the ester per se, such compositions may be provided separately from the body of'steel wool, e.g. in the form of a powder, cake, liquid, paste, cream or the like, to be applied to the steel wool or used in conjunction therewith at the time of scouring. Alternatively and preferably, however, such detergent compositions are combined with the instant esters to form a fluid, e.g. paste, liquid or cream, or solid, erg. particulate or unitary, product which is used as .an integral part of a steel wool scouring pad, as by coating, impregnation, envelopment, or mechanical entrapment in or on the steel wool.

Organic detergents which are preferably used in conjunction with or as part of a body of steel wool employed with an aliphatic phosphate ester according to the instant invention include anionic, non-ionic and amphoteric nonsoap detergents, especially those which generate at least about mm. of foam at 0.1% concentration by weight in the Ross-Miles pour foam test (see Ross and Miles, Oil and Soap, May 1941, pages 99-102; or see Ross and Miles, US. Patent 2,315,983). Suitable such anionic detergents are well known and include alkali metal and alkaline earth salts of various organic sulfates and sulfonates such as the higher alkyl aryl sulfonates, e.g., the sulfonates of alkylated benzene, toluene, cresol, naphthalene and the like in which the alkyl group contains from about 10 to 18 carbon atoms, for instance, sodium pentadecyl benzene sulfonate and sodium tetrapropylene benzene sulfonate; higher fatty alcohol sulfates such as potassium lauryl sulfate and the lithium salt of sulfated alcohols derived from coconut oil by reduction; sulfated higher'fatty acid 'monoglycerides such as the sodium or magnesium salts of monosulfated glyceryl monomyristate; and the higher fatty acid N-substituted taurates such as sodium N-methyl N-oleoyl'taurate. Amphoteric detergents which may be used alone or in admixture with other detergents include water soluble salts of N-higher alkyl beta-aminopropionic acid such as the triethanolamine salt 'of-N-lauryl'beta-alanine, and the sodium salt of N-higher alkyl beta iminodipropionic acid, the water soluble salts of higher-alkyl substituted quaternary hydroxy'cycloimidinic'acid metal alcoholates such as the disodium salt of "l-(z hydroxyethyl)-l-(carboxymethyl)- 2 hendecyl-4,5 dihydro-imidazolinium hydroxide, and water soluble salts of trialkyl ammonium carboxylic acids such as the sodium salt of lauryldimethylammonium aceticacid. Suitable non-ionic detergents includethe solid-water-soluble ethylene oxide condensates of waterinsoluble (molecular weight 900 to 2,400) polypropylene glycols, and thehigher fatty acid alkanolamides such as lauric monoand di-ethanolamide. Although it is preferred touse normally solid synthetic detergents, normally' liquid high'foaming detergents such as the ethylene oxide condensates of alkyl phenols, e.g., nonyl phenol condensed with from 6 to 16 mols of ethylene oxide, may also beused, in which case they may, if desired, be mixed with sufficient buffer salt, starch or similar solid material to absorb the liquid and in effect, convert the detergent to a normally solid form.

While it is preferred that the present steel Wool products befree of or used in the absence-of higher fatty acid soap (in'view of itstendency to become rancid and to form insoluble curds on-exposure to hard water), some soap may be present. In such cases, it is desirable to also have present sufficient non-soap organic detergent to protect the soap from the harmful effects of hard water.

The beneficial properties of the instant phosphate esters are especially significant in that they remain at a high level of efficacy in the presence of inorganic salts, which are generally antagonistic toward potential aluminum polishing agents for use in conjunction with steel wool. In view-of this surprising and unexpected beneficialeifect, it is particularly preferred to employ the instant phosphate esters in conjunction with one or more inorganic alkaline buffer'salts, which of course'offer the desirable charac- -teristic of inhibiting rusting of steel wool. Examples of such alkaline bufler salts are alkali metal detergent builder salts such as the alkali metal carbonates, e.g., sodium carbonate, sodium sesquicarbonate, and sodium bicarbonate, as well as sodium and potassium silicates, 'borax, and alkali'metal phosphates such as pentasodium tripolyphosphate, tetrasodium pyrophosphate and trisodiumphosphate. It is particularly preferred to use the non-phosphate buffers such as sodium carbonate as it hasbeen found; that the beneficial properties of the instant organic-esters are maintained at their highest levels in the absence of-inorganic phosphate salts.

If desired, the present phosphate esters may be com- 'bined'with appropriate detergents, plasticizers, and optionally'but preferably, with inorganic alkaline detergent builders to form permanently plastic paste-fillers'for steel wool pads. Suitableplasticizers for such paste-fillers include liquid or fluid, essentially non-volatile, water soluble or dispersible non-ionic surface active agents such as the normallyfiuid alkylolamides of higher fatty acids containing to 18 carbon atoms, for example, thediethanolamides of oleic or coconut oil'fatty-aci'ds, and'the correspondingfluid glycerolamides, as well as the wellknown'liquid non-ironic detergents of the ethylene oxide condensate type, e.g., ethylene oxide condensates of higherfatty acids, fatty acid amides, and C alkyl phenols.

The instant organic phosphate ester is employed in a small but effective amount suflicient to exert a polishing action on aluminum during scouring thereof by steel wool in the presence of an aqueous medium. The exact minimum amount necessary to such action, as well as the anti-seizing and hydrophobic film-forming action exhibited by the instant esters, is dependent upon the fiber diameter of steel wool employed, the metallurgical properties of the steel wool and aluminum to'be scoured, and the types and amount of other constituents present'in the pad, particularly inorganic salts. Thus inthe case of steel wool per se, very small amounts may sufiice, e.g. amounts as little as 0.01% by weight of the steel wool, or less, whereas in the case of-steel wool pads containing additional constitutents, increased proportions may be required. Suitable proportions will be illustrated by the examples hereinafter set forth, however an eminently satisfactory permanently plastic detergent paste-filler for charging of steel wool pads may be prepared within the following ranges of proportions:

Percent by Weight Suitable Preferred Partial ester of phosphoric acid and aliphatic alcohol 2720 5-l0 Water soluble detergent 1-60 20-40 Surface active non-ionic plasticizer 5-65 10 40 Water soluble inorganic alkaline buffer sa1t. 0-65 20-60 The following examples are given to illustrate the nature of the invention andit will be understood that the invention is not limited thereto. All-parts are percentages are by weight unless otherwisespecified.

Example I A. permanently plastic paste filler for steel wool scouring pads consists 10f:

Percent Disodium monolauryl orthophosphate 7 Diethanolamide of coconut oil fatty acids .18 sodiumidodecyl benzenesulfonate (containing about 15% vsodium sulfate) 30 Sodium carbonate (anhydrous) 45 In preparing loaded pads, the-above ingredients are mixed to form a uniform, permanently plastic detergent paste, grams of this paste are spread along one face of a strip of 0 gauge steel wool weighing7 grams, the strip isrolled up with the paste-carrying face on the inside, and the pad is then compressed to impart a desired shape and'form.

When used to scour aluminum cooking vessels, these pads arefound to foam copiously in the wash water, to scour and remove soil effectively without scratching, seizing or dragging on the vessel, and to confer a high polish to the scoured surface and leave it with a smooth, glossy surface which quickly drains substantially completely'free of water after rinsing.

The same results may be achieved if the disodium monolauryl phosphate of the foregoing example is replaced by unneutralized mixed primary and secondary acidic esters of lauryl alcoholand orthophosphoric acid (in a ratio of approximately 5:4 by weight).

Example III A scouring pad exhibiting excellent polishing properties on aluminum may be prepared as set forth in Example II using a paste having the following composition:

Parts by weight Monoisopropanolamide of coconut oil fatty acids 20 Detergent (88% sodium dodecyl benZene-sulfonate,

12% sodium sulfate) 30 Disodium monolauryl orthophosphate 5 Sodium carbonate 45 If desired, the detergent of this example may be replaced by sodium lauryl sulfate or the sodium or potassium salt of a sulfated monoglyceride of coconut oil fatty acids.

Example IV The following composition may be used in lieu of that of Example II to achieve substantially the same results:

Parts by weight Diethanolamide of coconut oil fatty acids 25 Detergent of Example III 58 R Na (P O where R is Z-ethyl hexyl 17 Example V Pads prepared containing the following mixed monoand di-esters in lieu of the partial phosphate ester of Example IV exhibit substantially the same properties as those of Example IV: sodium butyl orthophosphate, sodium Z-ethyl hexyl orthophosphate, sodium stearyl phosphate, and sodium oleyl phosphate.

Example VI The amphoteric detergent of the foregoing example may, if desired, be replaced by the disodium salt of 1- Z-hydroxyethyl 1 (carboxymethyl -2-(higher alkyl) 4,S-dihydro-imidazolinium hydroxide wherein the higher alkyl group is derived from coconut oil fatty acids (Miranol CM).

Example VII A pad of steel wool Weighing 7 grams is impregnated with 10 grams of the following composition:

Parts by weight Magnesium lauryl phosphate, monoesterzdiester =5:4 6.0 Diethanolamide of coconut oil fatty acids 18.0 Sodium dodecyl benzene sulfonate (containing about sodium sulfate) 30.0 Sodium carbonate 45.0 Moisture 1.0

The resulting pad foams well in water, and when used in the dishpan in the course of scouring and cleansing soiled aluminum cooking vessels, readily removes soil therefrom without scratching, seizing or dragging on the aluminum surfaces of the vessels. The vessels are polished and left with a smooth, glossy surface which quickly drains free of water after rinsing.

Although the present invention has been described with reference to particular embodiments and examples, it

will be apparent to those skilled in the art that variation and modification of this invention can be made and that equivalents can be substituted therefor without departing from the principles and true spirit of the invention. Thus one may, if desired, incorporate in the instant scouring pads a wide variety of adjuvants including perfumes, coloring agents, organic and inorganic corrosion inhibitors, abrasives such as alumina, organic sequestering agents such as ethylene diamine tetraacetic acid and its salts, and the like, without departing from the true scope of the invention as defined in the appended claims.

What is claimed is:

l. A process for polishing aluminum which comprises scouring aluminum with steel wool in the presence of an aqueous medium and partial ester of phosphoric acid and an aliphatic alcohol.

2. A process for polishing aluminum which comprises scouring aluminum with steel wool in the presence of water and an acidic partial ester of phosphoric acid and an aliphatic alcohol.

3. A process for polishing aluminum which comprises scouring aluminum with steel wool in the presence of water and a salt of a partial ester of phosphoric acid and an aliphatic alcohol.

4. A process for polishing aluminum which comprises scouring aluminum with. steel wool in the presence of an aqueous medium, a water soluble inorganic alkaline. buffer salt, and a partial ester of phosphoric acid and an aliphatic alcohol.

5. A process for polishing aluminum as set forth in claim 4 carried out in the presence of an organic detergent.

6. A body of steel wool containing a partial ester of phosphoric acid and an aliphatic alcohol as an aluminum polishing agent.

7. A steel wool scouring pad impregnated with a salt of a partial ester of phosphoric acid and an aliphatic alcohol as an aluminum polishing agent.

-8. A steel wool scouring pad impregnated with an acidic partial ester of phosphoric acid and an aliphatic alcohol as an aluminum polishing agent.

9. A steel wool scouring pad containing a water soluble inorganic alkaline buffer salt and, as an aluminum polishing agent, a water soluble salt of a partial ester of phosphoric acid and an aliphatic alcohol.

10. A steel wool scouring pad as set forth in claim 9 wherein said inorganic salt is sodium carbonate.

11. A steel wool pad as set forth in claim 9 which contains a water soluble organic detergent.

12. A detergent-carrying steel wool scouring pad characterized by the ability to polish aluminum when rubbed thereon in the presence of water which comprises steel wool impregnated by a substantially non-aqueous permanently plastic detergent paste filler consisting essentially of a water soluble organic detergent, a water soluble inorganic alkaline buffer salt, and an alkali metal salt of a partial ester of phosphoric acid and an aliphatic alcohol.

13. A detergent-carrying steel Wool scouring pad characterized by the ability to polish aluminum when rubbed thereon in the presence of water which comprises steel wool impregnated by a substantially non-aqueous permanently plastic detergent paste filler consisting essentially of:

Percent Partial ester of phosphoric acid and an aliphatic alcohol 2-20 A water soluble detergent 1-60 Surface active non-ionic plasticizer 5-65 Water soluble inorganic alkaline buffer salt 0 -65 '14. A detergent-carrying steel wool scouring pad characterized by the ability to polish aluminum when rubbed thereon in the presence of water which comprises steel wool impregnated by a substantially non-aqueous peralcohol '510 Water soluble detergent 2040 Surface active nonrionic plasticizer 1040 Water solubleinorganic alkaline ,bufier salt 20-60 15. Steelwool impregnated with an alkali metal salt of a partial ester of orthophosphoric acid and an aliphatic alcohol containing from about 4 to 20 carbon atoms.

16..,Steel --wool impregnated with an alkalimetalsalt of a monoesterof or-thophosphoric acid and an aliphatic alcohol containingfrom. about 8. to 20rcarbon atoms.

17. Steel wool impregnated With disodium monolauryl orthophosphate.

18. Steel wool impregnated with a partial ester of a polypho sphoric. acid and an aliphatic alcohol.

19. Steel wool impregnated with sodium butyl orthophosphate. 7

20. A; process -for polishing aluminum with ,a metal wool which normally tends to ,;-r,oughen. and scratch aluminum when rubbed thereon whichcomprisesscouri-ng aluminum withlsuch metal woolin the presence of an aqueousmedium andwapartial-ester of phosphoric acid and an aliphatic alcohol.

21. A process for polishing aluminum with a fibrous scouring device which normally tends to roughen and scratch aluminum when rubbed thereon which comprises scouring aluminum with 'such fibrous device in the presence of an aqueous medium and a partial ester of phosphoric acid and an aliphatic alcohol.

References Cited in.the file of this patent UNITED'STAT ES PATENTS 1,109,670 Feidt Sept. 8, 1914 1,446,998 Vincent Feb. 27, 1923 1,549,411 Gravell Aug. 11, 1925 1,765,331 Gravell June 17, 1930 1 ,949,713 Gravell Mar. 6, 1934 2,005,619 Graves June 18, 1935 2,084,361 Vanderbilt June 22, 1937 2,483,135 Goldsmith et al Sept. 27, 1949 2,936,288 Coleman May 10, 1960 3,004,879 Whitby Oct. 17, 1961 3,010,853 Elliott Nov. 28, 1961 3,034,169 Vitale et al May, 15, 1962 OTHER REFERENCES Chemical Industries, October 1942: LI 4, pages 516- 521 relied on.

Surface Active Agents, Schwartz et al., Interscience Publishing Co. NY. (pages 232-233 relied on). 

1. A PROCESS FOR POLISHING ALUMINUM WHICH COMPRISES SCOURING ALUMINUM WITH STEEL WOOL IN THE PRESENCE OF AN AQUEOUS MEDIUM AND PARTIAL ETER OF PHOSPHORIC ACID AND AN ALIPHATIC ALCOHOL. 